Metal—support interaction effects in the liquid-phase selective hydrogenation of 1,4-butynediol with nickel catalysts supported on AlPO 4 and on other conventional non-reducible compounds

Abstract

The liquid-phase selective hydrogenation of 1,4-butynediol has been carried out on nickel catalysts at 20 wt.-% supported on different AlPO 4, AlPO 4Al 2O 3 and AlPO 4-SiO 2 systems. Furthermore, some conventional non-reducible compounds, such as SiO 2, Al 2O 3, active carbon or a natural sepiolite were also used as supports. In addition, the effects of nickel loading and NiCu alloying were studied using carbon as the metal support. The relative adsorption constants, K T,D, were also obtained from the relative reactivities, R T,D, obtained in the consecutive hydrogenation process and the corresponding individual hydrogenation rates of 1,4-butynediol and 1,4-butenediol. These values were used to follow the changes in the electronic structure of supported nickel crystallites. Besides, structural defects of supported-nickel crystallites such as ‘twin faults’, ‘stacking faults’ and ‘microstrains’, were determined by X-ray diffraction line broadening analysis. These parameters were used for measuring the participation of geometric support effects in the catalytic activity of supported nickel catalysts. TEM measurements coupled with digital image processing were also used to measure nickel particle sizes. Results obtained in the correlation between kinetic data and structural defects in supported-nickel crystallites as well as with textural and acid—basic properties of the supports indicated that electronic and geometric effects were simultaneously developed throughout metal—support interactions.